Processing liquid for suppressing pattern collapse of fine metal structure, and method for producing fine metal structure using same

This application is a 371 of PCT/JP2010/062273 filed Jul. 21, 2010 which claims foreign benefit to Japan 2009-185124 filed Aug. 7, 2009.

The present invention relates to a processing liquid for suppressing pattern collapse of a fine metal structure, and a method for producing a fine metal structure using the same.

The photolithography technique has been employed as a formation and processing method of a device having a fine structure used in a wide range of fields of art including a semiconductor device, a circuit board and the like. In these fields of art, reduction of size, increase of integration degree and increase of speed of a semiconductor device considerably proceed associated with the highly sophisticated demands on capabilities, which brings about continuous miniaturization and increase of aspect ratio of the resist pattern used for photolithography. However, the progress of miniaturization of a resist pattern causes pattern collapse as a major problem.

It has been known that upon drying a resist pattern from a processing liquid used in wet processing (which is mainly a rinsing treatment for washing away the developer solution) after developing the resist pattern, the collapse of the resist pattern is caused by the stress derived by the surface tension of the processing liquid. For preventing the collapse of the resist pattern, such methods have been proposed as a method of replacing the rinsing liquid by a liquid having a low surface tension using a nonionic surfactant, a compound soluble in an alcohol solvent, or the like (see, for example, Patent Documents 1 and 2), and a method of hydrophobizing the surface of the resist pattern (see, for example, Patent Document 3).

In a fine structure formed of a metal, a metal nitride, a metal oxide or the like (which may be hereinafter referred to as a fine metal structure, and a metal, a metal nitride and a metal oxide may be hereinafter referred totally as a metal) by the photolithography technique, the strength of the metal itself constituting the structure is larger than the strength of the resist pattern itself or the bonding strength between the resist pattern and the substrate, and therefore, the collapse of the structure pattern is hard to occur as compared to the resist pattern. However, associated with the progress of reduction of size, increase of integration degree and increase of speed of a semiconductor device and a micromachine, the pattern collapse of the structure is becoming a major problem due to miniaturization and increase of aspect ratio of the resist pattern. The fine metal structure has a surface state that is totally different from that of the resist pattern, which is an organic material, and therefore, unlike in the case of the collapse of the resist pattern there is no effective measure for preventing the pattern collapse of the structure. Accordingly, the current situation is that the degree of freedom on designing the pattern for producing a semiconductor device or a micromachine with reduced size, increased integration degree and increased speed is considerably impaired since the pattern is necessarily designed for preventing the pattern collapse.

Patent Document 1

JP-A-2004-184648

Patent Document 2

JP-A-2005-309260

Patent Document 3

JP-A-2006-163314

[ FIG. 1 ] The figure includes schematic cross sectional views of each production step of fine metal structures produced in Examples 1 to 48 and Comparative Examples 1 to 30.

[ FIG. 2 ] The figure includes schematic cross sectional views of each production step of fine metal structures produced in Examples 49 to 112 and Comparative Examples 31 to 70.

101 photoresist

102 silicon oxide

103 silicon nitride

104 silicon substrate

105 circular opening

106 cylindrical hole

107 metal (titanium nitride, tungsten or tantalum)

108 cylindrical hollow of metal (titanium nitride, tungsten or tantalum)

201 silicon oxide layer

202 polysilicon

203 photoresist

204 rectangular columnar opening

205 rectangular columnar hole 205

206 rectangular column of metal (titanium, aluminum oxide, hafnium oxide or ruthenium)

207 metal (titanium, aluminum oxide, hafnium oxide or ruthenium) layer

208 photoresist

209 rectangular photomask

210 metal (titanium, aluminum oxide, hafnium oxide or ruthenium) plate

211 bridge structure

Disclosure of the Invention

Problems to be Solved by the Invention

As described above, the current situation is that no effective technique for suppressing pattern collapse has been known in the field of a fine metal structure, such as a semiconductor device and a micromachine.

The present invention has been developed under the circumstances, and an object thereof is to provide a processing liquid that is capable of suppressing pattern collapse of a fine metal structure, such as a semiconductor device and a micromachine, and a method for producing a fine metal structure using the same.

Means for Solving the Problems

As a result of earnest investigations made by the inventors for achieving the object, it has been found that the object can be achieved with a processing liquid containing a phosphate ester and/or a polyoxyalkylene ether phosphate ester.

The present invention has been completed based on the finding. Accordingly, the gist of the present invention is as follows.

(1) A processing liquid for suppressing pattern collapse of a fine metal structure, containing a phosphate ester and/or a polyoxyalkylene ether phosphate ester.

(2) The processing liquid according to the item (1), wherein the phosphate ester and/or the polyoxyalkylene ether phosphate ester is represented by the following general formula (1) and/or the following general formula (2):

wherein R 1 represents an alkyl group having from 2 to 24 carbon atoms or an alkenyl group having from 2 to 24 carbon atoms; and R 2 represents an alkanediyl group or an alkenediyl group having from 2 to 6 carbon atoms, in which plural groups represented by R 1 or R 2 may be the same as or different from each other; and n represents a number of from 0 to 20, in which plural numbers represented by n may be the same as or different from each other.

(3) The processing liquid according to the item (1) or (2), which further contains water.

(4) The processing liquid according to any one of the items (1) to (3), wherein OR 2 in the general formulae (1) and (2) is an oxyethylene group and/or an oxypropylene group.

(5) The processing liquid according to any one of the items (1) to (4), wherein a content of the phosphate ester and/or the polyoxyalkylene ether phosphate ester is from 10 ppm to 50%.

(6) The processing liquid according to any one of the items (1) to (5), wherein the pattern of the fine metal structure contains at least one material selected from titanium nitride, titanium, ruthenium, ruthenium oxide, tungsten, tungsten silicide, tungsten nitride, aluminum oxide, hafnium oxide, hafnium silicate, hafnium nitride silicate, platinum, tantalum, tantalum oxide, tantalum nitride, nickel silicide, nickel silicon germanium and nickel germanium.

(7) A method for producing a fine metal structure, containing after wet etching or dry etching, a rinsing step using the processing liquid according to any one of the items (1) to (6).

(8) The production method according to the item (7), wherein the pattern of the fine metal structure contains at least one material selected from titanium nitride, titanium, ruthenium, ruthenium oxide, tungsten, tungsten silicide, tungsten nitride, aluminum oxide, hafnium oxide, hafnium silicate, hafnium nitride silicate, platinum, tantalum, tantalum oxide, tantalum nitride, nickel silicide, nickel silicon germanium and nickel germanium.

(9) The production method according to the item (7) or (8), wherein the fine metal structure is a semiconductor device or a micromachine.

According to the present invention, there are provided a processing liquid that is capable of suppressing pattern collapse of a fine metal structure, such as a semiconductor device and a micromachine, and a method for producing a fine metal structure using the same.

Best Mode For Carrying Out The Invention

Processing Liquid

The processing liquid of the present invention is used for suppressing pattern collapse of a fine metal structure, and contains a phosphate ester and/or a polyoxyalkylene ether phosphate ester.

Phosphate Ester and Polyoxyalkylene Ether Phosphate Ester

It is considered that the phosphate ester and the polyoxyalkylene ether phosphate ester used in the processing liquid of the present invention are adsorbed on the metal material used in the pattern of the fine metal structure, thereby hydrophobizing the surface of the pattern. The hydrophobization in the present invention means that the contact angle of the metal surface having been processed with the processing liquid of the present invention with respect to water is 70° or more. The phosphate ester and the polyoxyalkylene ether phosphate ester generally contain a monoester and a diester simultaneously, and a monoester or a diester may be used solely. Preferred examples of the phosphate ester and the polyoxyalkylene ether phosphate ester include compounds represented by the following general formula (1) and/or the following general formula (2):

In the formulae, R 1 represents an alkyl group having from 2 to 24 carbon atoms or an alkenyl group having from 2 to 24 carbon atoms. The alkyl group is preferably an alkyl group having from 6 to 18 carbon atoms, more preferably an alkyl group having from 12 to 18 carbon atoms, further preferably an alkyl group having 12, 13 or 18 carbon atoms, and particularly preferably an alkyl group having 18 carbon atoms. The alkyl group may be linear, branched or cyclic, and may have a halogen atom or a substituent. Examples of the alkyl group include various kinds of hexyl groups, such as a n-hexyl group, a 1-methylhexyl group, a 2-methylhexyl group, a 1-pentylhexyl group, a cyclohexyl group, a 1-hydroxyhexyl group, a 1-chlorohexyl group, 1,3-dichlorohexyl group, a 1-aminohexyl group, a 1-cyanohexyl group and a 1-nitrohexyl group, and also include various kinds of heptyl groups, various kinds of octyl groups, various kinds of nonyl groups, various kinds of decyl groups, various kinds of undecyl groups, various kinds of dodecyl groups, various kinds of tridecyl groups, various kinds of tetradecyl groups, various kinds of pentadecyl groups, various kinds of hexadecyl groups, various kinds of heptadecyl groups, various kinds of octadecyl groups, various kinds of nonadecyl groups and various kinds of eicosyl groups. Preferred examples of the alkyl group include various kinds of hexyl groups, and also include various kinds of heptyl groups, various kinds of octyl groups, various kinds of nonyl groups, various kinds of decyl groups, various kinds of undecyl groups, various kinds of dodecyl groups, various kinds of tridecyl groups, various kinds of tetradecyl groups and various kinds of octadecyl groups, and more preferably various kinds of dodecyl groups, various kinds of tridecyl groups and various kinds of octadecyl groups. Plural groups represented by R 1 in the formula (2) may be the same as or different from each other.

The alkenyl group is preferably an alkenyl group having from 2 to 24 carbon atoms, more preferably an alkenyl group having from 4 to 18 carbon atoms, further preferably an alkenyl group having from 6 to 18 carbon atoms, and particularly preferably an oleyl group having 18 carbon atoms. The alkenyl group may be linear or branched.

In the formulae, R 2 represents an alkanediyl group or an alkenediyl group having from 2 to 6 carbon atoms, and plural groups represented by R 2 may be the same as or different from each other.

The alkanediyl group having from 2 to 6 carbon atoms may be linear or branched, and examples thereof include an ethylene group, a 1,2-propanediyl group, a 1,3-propanediyl group, various kinds of butanediyl groups, various kinds of pentanediyl groups and various kinds of hexanediyl groups. Preferred examples among these include linear groups, such as an ethylene group, a 1,3-propanediyl group, a 1,4-butanediyl group, 1,5-pentanediyl group and 1,6-hexanediyl group, and particularly preferred examples include an ethylene group and a 1,2-propanediyl group. Accordingly, particularly preferred examples of OR 2 include an oxyethylene group and an oxypropylene group.

In the formulae, n represents a number of from 0 to 20, and preferably from 0 to 14. When n is in the range, the phosphate ester and/or the polyoxyalkylene ether phosphate ester used in the present invention is in a liquid state and is easily soluble in a solvent, such as water or an organic solvent, to form the processing liquid favorably, while depending on the balance between hydrophilicity and hydrophobicity of the functional group represented by R 1 in the formulae.

In the present invention, the compound represented by the general formula (1) or (2) is preferably an alkyl phosphate ester or a polyoxyalkylene alkyl ether phosphate ester, in which R 1 and R 3 each are an alkyl group, and R 2 is an alkanediyl group, an alkenyl phosphate ester or a polyoxyalkylene alkenyl ether phosphate ester, in which R 1 is an alkenyl group, and R 2 is an alkanediyl group or the like . Two groups represented by R 1 in the general formula (2) may be the same as or different from each other. The use of the aforementioned compounds makes the processing liquid of the present invention exhibit the excellent function of suppressing pattern collapse.

Particularly preferred examples of the compounds represented by the general formulae (1) and (2) include an alkyl phosphate ester, such as an octyl phosphate ester, a lauryl phosphate ester, a tridecyl phosphate ester and a compound represented by the general formula (2), in which n is 0, and R 1 is a mixture of groups having from 6 to 10 carbon atoms (from hexyl to decyl); a polyoxyethylene alkyl ether phosphate ester, such as a polyoxyethylene hexyl ether phosphate ester (n: 1 to 8), a polyoxyethylene heptyl ether phosphate ester (n: 1 to 8), a polyoxyethylene octyl ether phosphate ester (n: 1 to 8), a polyoxyethylene nonenyl ether phosphate ester (n: 1 to 8), a polyoxyethylene decyl ether phosphate ester (n: 1 to 12), a polyoxyethylene lauryl ether phosphate ester (n: 1 to 12), a polyoxyethylene tridecyl ether phosphate ester (n: 1 to 12) and a polyoxyethylene stearyl ether phosphate ester (n: 1 to 12); a polyoxyethylene alkenyl ether phosphate ester, such as polyoxyethylene oleyl ether phosphate ester (n: 1 to 12); a polyoxyethylene polyoxypropylene alkyl ether phosphate ester, such as a polyoxyethylene polyoxypropylene nonenyl ether phosphate ester (n: 1 to 8), a polyoxyethylene polyoxypropylene decyl ether phosphate ester (n: 1 to 10), a polyoxyethylene polyoxypropylene undecyl ether phosphate ester (n: 1 to 8), a polyoxyethylene polyoxypropylene dodecyl ether phosphate ester (n: 1 to 8), a polyoxyethylene polyoxypropylene tridecyl ether phosphate ester (n: 1 to 8) and a polyoxyethylene polyoxypropylene tetradecyl ether phosphate ester (n: 1 to 8); and mixtures of these compounds.

Water

The processing liquid of the present invention preferably further contains water and is preferably an aqueous solution. Preferred examples of the water include water, from which metallic ions, organic impurities, particles and the like are removed by distillation, ion exchange, filtering, adsorption treatment or the like, and particularly preferred examples thereof include pure water and ultrapure water.

Processing Liquid

The processing liquid of the present invention contains the phosphate ester and the polyoxyalkylene ether phosphate ester described above, preferably contains water, and may contain various kinds of additives that are ordinarily used in processing liquids in such a range that does not impair the advantages of the processing liquid.

The content of the phosphate ester and the polyoxyalkylene ether phosphate ester in the processing liquid of the present invention is preferably from 10 ppm to 50%. When the content of the phosphate ester and the polyoxyalkylene ether phosphate ester is in the range, the advantages of the compounds may be sufficiently obtained. In consideration of handleability, economy and foaming, the compounds are used preferably at a lower concentration of 10% or less, more preferably from 10 to 2,000 ppm, and further preferably from 10 to 1,000 ppm.

In the case where the compounds do not have sufficient solubility in water to cause phase separation, an organic solvent, such as an alcohol, may be added, and an acid or an alkali may be added to enhance the solubility. Even in the case where the processing liquid is simply turbid white without phase separation, the processing liquid may be used in such a range that does not impair the advantages of the processing liquid, and may be used while stirring to make the processing liquid homogeneous. Furthermore, for avoiding the white turbidity of the processing liquid, the processing liquid may be used after adding an organic solvent, such as an alcohol, an acid or an alkali thereto as similar to the above case.

The processing liquid of the present invention may be used favorably for suppressing pattern collapse of a fine metal structure, such as a semiconductor device and a micromachine. Preferred examples of the pattern of the fine metal structure include ones containing at least one material selected from TiN (titanium nitride), Ti (titanium), Ru (ruthenium), RuO (ruthenium oxide), SrRuO 3 (SRO), W (tungsten), WSi (tungsten silicide), WN (tungsten nitride), Al 2 O 3 (aluminum oxide), HfO 2 (hafnium oxide), HfSiO x (hafnium silicate), HfSiON (hafnium nitride silicate), Pt (platinum), Ta (tantalum), Ta 2 O 5 (tantalum oxide), TaN (tantalum nitride), NiSi (nickel silicide), NiSiGe (nickel silicon germanium) and NiGe (nickel germanium), more preferred examples thereof include TiN (titanium nitride), Ti (titanium), Ru (ruthenium), RuO (ruthenium oxide), SrRuO 3 (SRO), W (tungsten), WSi (tungsten silicide), Al 2 O 3 (aluminum oxide), HfO 2 (hafnium oxide), Pt (platinum), Ta (tantalum), Ta 2 O 5 (tantalum oxide) and TaN (tantalum nitride), and further preferred examples thereof include TiN (titanium nitride), W (tungsten), Ta (tantalum), Ti (titanium), Al 2 O 3 (aluminum oxide), HfO 2 (hafnium oxide) and Ru (ruthenium).

The fine metal structure may be patterned on an insulating film species, such as SiO 2 (a silicon oxide film) and TEOS (a tetraethoxy ortho silane oxide film), in some cases, or the insulating film species is contained as a part of the fine metal structure in some cases.

The processing liquid of the present invention exhibits excellent pattern collapse suppressing effect to not only an ordinary fine metal structure, but also a fine metal structure with further miniaturization and higher aspect ratio. The aspect ratio referred herein is a value calculated from (height of pattern/width of pattern), and the processing liquid of the present invention has excellent pattern collapse suppressing effect to a pattern that has a high aspect ratio of 3 or more, and further 7 or more. The processing liquid of the present invention has excellent pattern collapse suppressing effect to a fine pattern with a pattern size of 300 nm or less, further 150 nm or less, and still further 100 nm or less, and with a pattern size of 50 nm or less and a line/space ratio of 1/1, and similarly to a fine pattern with a pattern distance of 300 nm or less, further 150 nm or less, still further 100 nm or less, and still further 50 nm or less and a cylindrical hollow or cylindrical solid structure.

Method for producing Fine Metal Structure

The method for producing a fine metal structure of the present invention contains, after wet etching or dry etching, a rinsing step using the processing liquid of the present invention. More specifically, in the rinsing step, it is preferred that the pattern of the fine metal structure is made in contact with the processing liquid of the present invention by dipping, spray ejecting, spraying or the like, then the processing liquid is replaced by water, and the fine metal structure is dried. In the case where the pattern of the fine metal structure and the processing liquid of the present invention are in contact with each other by dipping, the dipping time is preferably from 10 seconds to 30 minutes, more preferably from 15 seconds to 20 minutes, further preferably from 20 seconds to 15 minutes, and particularly preferably from 30 seconds to 10 minutes, and the temperature condition is preferably from 10 to 60° C., more preferably from 15 to 50° C., further preferably from 20 to 40° C., and particularly preferably from 25 to 40° C. The pattern of the fine metal structure may be rinsed with water before making in contact with the processing liquid of the present invention. The contact between the pattern of the fine metal structure and the processing liquid of the present invention enables suppression of collapse of the pattern through hydrophobization of the surface of the pattern.

The processing liquid of the present invention may be applied widely to a production process of a fine metal structure irrespective of the kind of the fine metal structure, as far as the production process has a step of wet etching or dry etching, then a step of wet processing (such as etching, cleaning or rinsing for washing the cleaning liquid), and then a drying step. For example, the processing liquid of the present invention may be favorably used after the etching step in the production process of a semiconductor device or a micromachine, for example, (i) after wet etching of an insulating film around an electroconductive film in the production of a DRAM type semiconductor device (see, for example, JP-A-2000-196038 and JP-A-2004-288710), (ii) after a rinsing step for removing contamination formed after dry etching or wet etching upon processing a gate electrode in the production of a semiconductor device having a transistor with a fin in the form of strips (see, for example, JP-A-2007-335892), and (iii) after a rinsing step for removing contamination formed upon etching for forming a cavity by removing sacrifice layer formed of an insulating film through a through hole in an electroconductive film upon forming a cavity of a micromachine (electrodynamic micromachine) (see, for example, JP-A-2009-122031).

The present invention will be described in more detail with reference to examples and comparative examples below, but the present invention is not limited to the examples.

Preparation of Processing Liquid

Processing liquids for suppressing pattern collapse of a fine metal structure of Examples 1 and 2 were prepared according the formulation compositions (% by mass) shown in Table 1.

Examples 1 to 16

As shown in FIG. 1( a ), silicon nitride 103 (thickness: 100 nm) and silicon oxide 102 (thickness: 1,200 nm) were formed as films on a silicon substrate 104 , then a photoresist 101 was formed, and the photoresist 101 was exposed and developed, thereby forming a circular and ring-shaped opening 105 (diameter: 125 nm, distance between circles: 50 nm), as shown in FIG. 1( b ). The silicon oxide 102 was etched by dry etching with the photoresist 101 as a mask, thereby forming a cylindrical hole 106 reaching the layer of silicon nitride 103 , as shown in FIG. 1( c ). The photoresist 101 was then removed by ashing, thereby providing a structure having the silicon oxide 102 with the cylindrical hole 106 reaching the layer of silicon nitride 103 , as shown in FIG. 1( d ). The cylindrical hole 106 of the resulting structure was filled with titanium nitride as a metal 107 ( FIG. 1( e )), and an excessive portion of the metal (titanium nitride) 107 on the silicon oxide 102 was removed by chemical mechanical polishing (CMP), thereby providing a structure having the silicon oxide 102 with a cylindrical hollow of the metal (titanium nitride) 108 embedded therein, as shown in FIG. 1( f ). The silicon oxide 102 of the resulting structure was removed by dissolving with hydrofluoric acid, and then the structure was processed by making into contact with pure water, the processing liquids 1 to 16, and pure water in this order, followed by drying, thereby providing a structure shown in FIG. 1( g ).

The resulting structure had a fine structure with a chimney pattern containing cylindrical hollows of the metal (titanium nitride) (diameter: 125 nm, height: 1,200 nm (aspect ratio: 9.6), distance between the cylindrical hollows: 50 nm), and 70% or more of the pattern was not collapsed.

The pattern collapse was observed with “FE-SEM S-5500 (model number)”, produced by Hitachi High-Technologies Corporation, and the collapse suppression ratio was a value obtained by calculating the ratio of the pattern not collapsed in the total pattern. Cases where the collapse suppression ratio was 50% or more were determined as passed. The compositions of the processing liquids 1 to 16 used in the examples are shown in Table 1, and the processing liquids, the processing methods and the results of collapse suppression ratios in the examples are shown in Table 3.

Comparative Example 1

A structure shown in FIG. 1( g ) was obtained in the same manner as in Example 1 except that after removing the silicon oxide 102 of the structure shown in FIG. 1( f ) by dissolving with hydrofluoric acid, the structure was processed only with pure water. 50% or more of the pattern of the resulting structure was collapsed as shown in FIG. 1( h ) (which indicated a collapse suppression ratio of less than 50%. The processing liquid, the processing method and the result of collapse suppression ratio in Comparative Example 1 are shown in Table 3.

Comparative Examples 2 to 10

Structures shown in FIG. 1( g ) of Comparative Examples 2 to 10 were obtained in the same manner as in Example 1 except that after removing the silicon oxide 102 of the structure shown in FIG. 1( f ) by dissolving with hydrofluoric acid and being processed with pure water, the structures were processed with the comparative liquids 1 to 9 shown in Table 2 instead of the processing liquid 1 . 50% or more of the pattern of the resulting structures was collapsed as shown in FIG. 1( h ). The compositions of the comparative liquids 1 to 9 used in Comparative Examples 2 to 10 are shown in Table 2, and the comparative liquids, the processing methods and the results of collapse suppression ratios in the comparative examples are shown in Table 3.

Examples 17 to 32

Structures shown in FIG. 1( g ) of Examples 17 to 32 were obtained in the same manner as in Examples 1 to 16 except that tungsten was used as the metal 107 instead of titanium nitride. The resulting structures had a fine structure with a pattern containing cylindrical hollows 108 of the metal (tungsten) (diameter: 125 nm, height: 1,200 nm (aspect ratio: 9.6), distance between the cylindrical hollows: 50 nm), and 70% or more of the pattern was not collapsed. The compositions of the processing liquids 1 to 16 used in the examples are shown in Table 1, and the processing liquids, the processing methods and the results of collapse suppression ratios in the examples are shown in Table 4.

Comparative Examples 11 to 20

Structures shown in FIG. 1( g ) of Comparative Examples 11 to 20 were obtained in the same manner as in Comparative Examples 1 to 10 except that tungsten was used as the metal 107 instead of titanium nitride. 50% or more of the pattern of the resulting structures was collapsed as shown in FIG. 1( h ). The compositions of the comparative liquids 1 to 9 used in the comparative examples are shown in Table 2, and the comparative liquids, the processing methods and the results of collapse suppression ratios in the comparative examples are shown in Table 4.

Examples 33 to 48

Structures shown in FIG. 1( g ) of Examples 33 to 48 were obtained in the same manner as in Examples 1 to 16 except that tantalum was used as the metal 107 instead of titanium nitride. The resulting structures had a fine structure with a pattern containing cylindrical hollows 108 of the metal (tantalum) (diameter: 125 nm, height: 1,200 nm (aspect ratio: 9.6), distance between the cylindrical hollows: 50 nm), and 70% or more of the pattern was not collapsed. The compositions of the processing liquids 1 to 16 used in the examples are shown in Table 1, and the processing liquids, the processing methods and the results of collapse suppression ratios in the examples are shown in Table 5.

Comparative Examples 21 to 30

Structures shown in FIG. 1( g ) of Comparative Examples 21 to 30 were obtained in the same manner as in Comparative Examples 1 to 10 except that tantalum was used as the metal 107 instead of titanium nitride. 50% or more of the pattern of the resulting structures was collapsed as shown in FIG. 1( h ). The compositions of the comparative liquids 1 to 9 used in the comparative examples are shown in Table 2, and the comparative liquids, the processing methods and the results of collapse suppression ratios in the comparative examples are shown in Table 5.

Examples 49 to 64

As shown in FIG. 2( a ), polysilicon 202 (thickness: 100 nm) was formed on a silicon oxide layer 201 formed on a silicon substrate, and after forming a photoresist 203 thereon, the photoresist 203 was exposed and developed, thereby forming a rectangular columnar opening 204 (1,000 nm×8,000 nm) as shown in FIG. 2( b ) was formed. The polysilicon 202 was dry etched with the photoresist 203 as a mask, thereby forming a rectangular columnar hole 205 therein reaching the silicon oxide layer 201 as shown in FIG. 2( c ). The photoresist 203 was then removed by ashing, thereby providing a structure having the polysilicon 202 with the rectangular columnar hole 205 therein reaching the silicon oxide layer 201 as shown in FIG. 2( d ). The rectangular columnar hole 205 of the resulting structure was filled with titanium, thereby forming a rectangular column of a metal (titanium) 206 and a metal (titanium) layer 207 ( FIG. 2( e )), and a photoresist 208 was formed on the metal (titanium) layer 207 ( FIG. 2( f )). The photoresist 208 was exposed and developed, thereby forming a photomask 209 having a rectangular shape covering the area including the two rectangular columns of a metal (titanium) 206 as shown in FIG. 2( g ), and the metal (titanium) layer 207 was dry etched with the rectangular photomask 209 as a mask, thereby forming a metal (titanium) plate 210 having the rectangular columns of a metal (titanium) 206 at both the ends of the lower part thereof as shown in FIG. 2( h ). The rectangular photomask 209 was then removed by ashing, thereby providing a structure having the polysilicon 202 and the metal (titanium) plate 210 having the rectangular columns of a metal (titanium) 206 as shown in FIG. 2( i ). The polysilicon 202 of the resulting structure was removed by dissolving with a tetramethylammonium hydroxide aqueous solution, and then the structure was processed by making into contact with pure water, the processing liquids 1 to 16 , and pure water in this order, followed by drying, thereby providing a bridge structure 211 shown in FIG. 2( j ) of Examples 49 to 64.

The resulting bridge structure 221 had a fine structure with the metal (titanium) plate 210 (length×width: 15,000 nm×10,000 nm, thickness: 300 nm, aspect ratio: 50) and the rectangular columns of a metal (titanium) (length×width: 1,000 nm×8,000 nm, height: 100 nm) at both the ends thereof, and 70% or more of the metal (titanium) plate 210 was not collapsed and was not in contact with the silicon oxide layer 201 . The pattern collapse was observed with “FE-SEM S-5500 (model number)”, produced by Hitachi High-Technologies Corporation. The compositions of the processing liquids 1 to 16 used in the examples are shown in Table 1, and the processing liquids, the processing methods and the results of collapse suppression ratios in the examples are shown in Table 6.

Comparative Example 31

A bridge structure 211 shown in FIG. 2( j ) was obtained in the same manner as in Example 49 except that after removing the polysilicon 202 of the structure shown in FIG. 2( i ) by dissolving with a tetramethylammonium hydroxide aqueous solution, the structure was processed only with pure water. 50% or more of the resulting bridge structures 211 was collapsed as shown in FIG. 2( k ). The processing liquid, the processing method and the result of collapse suppression ratio in Comparative Example 31 are shown in Table 6.

Comparative Examples 32 to 40

Bridge structures 211 shown in FIG. 2( j ) of Comparative Examples 32 to 40 were obtained in the same manner as in Example 49 except that after removing the polysilicon 202 of the structure shown in FIG. 2( i ) by dissolving with a tetramethylammonium hydroxide aqueous solution and being processed with pure water, the structure was processed with the comparative liquids 1 to 9 shown in Table 2 instead of the processing liquid 1 . 50% or more of the resulting bridge structures 211 was collapsed as shown in FIG. 2( k ) (which indicated a collapse suppression ratio of less than 50%). The compositions of the comparative liquids 1 to 9 used in Comparative Example 31 are shown in Table 2, and the comparative liquids, the processing methods and the results of collapse suppression ratios in the comparative examples are shown in Table 6.

Examples 65 to 80

Bridge structures 211 shown in FIG. 2( j ) of Examples 65 to 80 were obtained in the same manner as in Examples 49 to 64 except that aluminum oxide was used as the metal instead of titanium.

The resulting bridge structures 211 had a fine structure with the metal (aluminum oxide) plate 210 (length×width: 15,000 nm×10,000 nm, thickness: 300 nm, aspect ratio: 50) and the rectangular columns of a metal (aluminum oxide) (length×width: 1,000 nm×8,000 nm, height: 100 nm) at both the ends thereof, and 70% or more of the metal (aluminum oxide) plate 210 was not collapsed and was not in contact with the silicon oxide layer 201 . The compositions of the processing liquids 1 to 16 used in the examples are shown in Table 1, and the processing liquids, the processing methods and the results of collapse suppression ratios in the examples are shown in Table 7.

Comparative Examples 41 to 50

Bridge structures 211 shown in FIG. 2( j ) of Comparative Examples 41 to 50 were obtained in the same manner as in Comparative Examples 31 to 40 except that aluminum oxide was used as the metal instead of titanium. 50% or more of the resulting bridge structures was collapsed as shown in FIG. 2( k ).

The compositions of the comparative liquids 1 to 9 used in the comparative examples are shown in Table 2, and the comparative liquids, the processing methods and the results of collapse suppression ratios in the comparative examples are shown in Table 7.

Examples 81 to 96

Bridge structures 211 shown in FIG. 2( j ) of Examples 81 to 96 were obtained in the same manner as in Examples 49 to 64 except that hafnium oxide was used as the metal instead of titanium.

The resulting bridge structures 211 had a fine structure with the metal (hafnium oxide) plate 210 (length×width: 15,000 nm×10,000 nm, thickness: 300 nm, aspect ratio: 50) and the rectangular columns of a metal (hafnium oxide) (length×width: 1,000 nm×8,000 nm, height: 100 nm) at both the ends thereof, and 70% or more of the metal (hafnium oxide) plate 210 was not collapsed and was not in contact with the silicon oxide layer 201 . The compositions of the processing liquids 1 to 16 used in the examples are shown in Table 1, and the processing liquids, the processing methods and the results of collapse suppression ratios in the examples are shown in Table 8.

Comparative Examples 51 to 60

Bridge structures 211 shown in FIG. 2( j ) of Comparative Examples 51 to 60 were obtained in the same manner as in Comparative Examples 31 to 40 except that hafnium oxide was used as the metal instead of titanium. 50% or more of the resulting bridge structures was collapsed as shown in FIG. 2( k ). The compositions of the comparative liquids 1 to 9 used in the comparative examples are shown in Table 2, and the comparative liquids, the processing methods and the results of collapse suppression ratios in the comparative examples are shown in Table 8.

Examples 97 to 112

Bridge structures 211 shown in FIG. 2( j ) of Examples 97 to 112 were obtained in the same manner as in Examples 49 to 64 except that ruthenium was used as the metal instead of titanium.

The resulting bridge structures 211 had a fine structure with the metal (ruthenium) plate 210 (length×width: 15,000 nm×10,000 nm, thickness: 300 nm, aspect ratio: 50) and the rectangular columns of a metal (ruthenium) (length×width: 1,000 nm×8,000 nm, height: 100 nm) at both the ends thereof, and 70% or more of the metal (ruthenium) plate 210 was not collapsed and was not in contact with the silicon oxide layer 201 . The pattern collapse was observed with “FE-SEM S-5500 (model number)”, produced by Hitachi High-Technologies Corporation. The compositions of the processing liquids 1 to 16 used in the examples are shown in Table 1, and the processing liquids, the processing methods and the results of collapse suppression ratios in the examples are shown in Table 9.

Comparative Examples 61 to 70

Bridge structures 211 shown in FIG. 2( j ) of Comparative Examples 61 to 70 were obtained in the same manner as in Comparative Examples 31 to 40 except that ruthenium was used as the metal instead of titanium. 50% or more of the resulting bridge structures was collapsed as shown in FIG. 2( k ). The compositions of the comparative liquids 1 to 9 used in the comparative examples are shown in Table 2, and the comparative liquids, the processing methods and the results of collapse suppression ratios in the comparative examples are shown in Table 9.

The processing liquid of the present invention may be used favorably for suppressing pattern collapse in the production of a fine metal structure, such as a semiconductor device and a micromachine (MEMS).